A fuel rail is a device that transports fuel at a specified pressure and flow rate, from the fuel chassis lines to the fuel injectors. The fuel rails also maintain the position of the injectors, which aids in the correct spray pattern of the fuel to the intake valve.
A fuel rail, technically known as a common rail, is essentially a pipe (usually resembling a rail) used to deliver fuel to individual fuel injectors on internal combustion engines. It is designed to have a pocket or seat for each injector as well as an inlet for a fuel supply. Fuel rails are used on engines with multi-point fuel injection systems, although some multi-point systems use a fuel distributor with individual pipes or tubes to feed each injector. The main function of the fuel rail consists in the optimal distribution of the fuel (gasoline, methane, etc.) to the injectors in the high or low pressure supply systems of endothermic engines. This fuel rail is Hi Pressure because max pressure in Fuel Rail is between 6-12bar.